Plasma thermodynamics of the inner heliosphere with Solar Orbiter and Parker Solar Probe

One of the most important unanswered questions in astrophysics is: how do ions and electrons get hot in plasma that effectively has no collisions between particles? One way that we can directly investigate the heating processes is to observe an astrophysical plasma first hand by measuring the solar wind, the hot and fast outflow of plasma from the Sun. The solar wind hand has the interesting property that electrons in the flow are, on average, about 30% hotter than the ions. It is not known whether this difference in temperature is generated in the solar corona before the solar wind is launched into interplanetary space, or caused by local heating processes related to the dissipation of turbulence in the solar wind itself. Either way, the ions and electrons must be interacting with electromagnetic fields in the plasma to gain and distribute energy. To investigate exactly which mechanisms move energy between the ions, electrons, and the electromagnetic fields involves theoretical understanding of kinetic plasma physics and electromagnetism and data analysis of observations taken by spacecraft. The student will work to answer the questions: What processes heat ions and electrons near the Sun? Why are electrons hotter than ions? How does the expansion of the solar wind affect these heating and acceleration processes?

The student will use data recorded by the new ESA Solar Orbiter (SO) and NASA Parker Solar Probe (PSP) missions to measure at the ions, electrons and electromagnetic fields closed to the Sun than ever studied before. The primary work of the PhD will be data analysis using statistical analysis of large data sets and machine learning or other big-data analysis techniques.

The student will have the opportunity to present their work at national and international conferences and publish work in leading scientific journals. By the end of the PhD, the student will have learned scientific writing, coding for data analysis, methods for visualising data, presenting of complex material to a wide audience, and how to manage their own small projects. The student will participate in SO SWA meetings, learning how particle sensors designed for space science work and are operated, and work with the world-leading scientists of the SO and PSP missions.